The prime objective is to classify different types of leukocytes according to immunobiological property and chemical composition profiles. To do so we are developing new lines of cells in culture in order to better classify the cells. Differences are particularly significant when cell lines with different characteristics are obtained from the same individual. Two such pairs of T cells and B cells are already available from single individuals. Human lymphoid cell lines in culture retain a variety of biological functions characteristic of B or T cells which include production of MLR substances, human Ia-like antigens, sheep erythrocyte receptors and lymphokines in addition to immunoglobulins and HLA antigens. We are using these cells to investigate lymphocyte surface components, particularly glycoprotein components other than immunoglobulins and HLA antigens. We isolate surface components that are characteristic of human B or T leukocytes in order to reveal their basic structure and immunological significance. We are especially focusing on human Ia-like antigens on B cells and human TLa-like antigens on T cells.